Minimost XL modifications

[randyt]

Nice going, it looks like you've got things set up pretty well now. I can't figure out how you might slow down quicker without defying the laws of physics unless you pioneer some sort of boat brake.

Maybe you could squeeze out more speed with a higher pitched prop? Possibly, but I have heard this rule of thumb: each inch of pitch lowers RPM by 2000. Even with your flat-bottomed beauty the rule probably applies to some extent.

The prop issue will be next on the list . I have already sent some info , specs and pics to Ron Hill to see if he has some thoughts . I was out today and getting the hang of it a little better . I was able to set a fairly nose high attitude which is how I would deal with any large wakes but I did have to be in slow mode to do it .
Thanks for checking in

[randyt]

The prop does not free wheel so that’s a non issue . Movable tabs would be nice but just out of the price range for something that will be a two month a year play toy . You are correct about the foot activated cavitation plate on the racing inboards . Actually most “flat bottoms “ have movable plates , I think it’s the only way they can get the damn things to turn

Interesting thing on water brakes . I was in a shop today and saw a jet ski with the advertising blurb of “first pwc with a brake “. I wasn’t able to figure out how it worked but I will be back there .

I also was very happy to see the nose come back up . In Cat sailing we call that “ going down the mine “ . The key is to keep that from happening in the first place . As I get better with the boat itself that should be less of a worry .

Thanks again for the comments .

[randyt]

Well we have had the boat out several times now and its proving to be just what we were looking for. The motor is reliable and the boat is water free , even as far as any spillage coming in over the transom on a quick stop. The additional  height we added to the transom does a great job of blocking the following wake mush more than we ever planned. I have a 1100 gph bilge pump back their waiting just in case but I think its going to last a long time based on usage
I am able to go as slow as i want for exploring and we even used it for a week at the shore towing a tube .  I was shocked at how level it was when even towing two adults. With the addition of the trim tabs the boat also turns much better than before and I am not even going to upgrade to the larger skeg I bought as the smaller water ski fin is doing the job nicely.

I would like to see some more top end out of it and that will be the next phase of development . I have basically one more week with it and then I am back in CA until December. We are still at the stage where I max out at 35 smoothly and when i trim up just a little more you can actually feel the boat break free of the water and start to accelerate but the porpoising starts at the same time.

Here are some photos of the boat actually in the water

We had built a dolly to bring the boat in and out of the water to deal with the low tide situation but found it to be a real pain in the ass. We made a rectangular frame out of 4 inch PVC and would put it under the boat and tie it to the hull and just let the tide go out and the boat would settle onto the sand but be suspended on the frame . The tide would return and the boat would float itself while tied bow and stern of course. Much easier

[randyt]

Well we had a productive summer with the little boat , made some additions and had a little bit of progress . We are happy with the results so far and it does everything i wanted it to do but knowing there is more to be had as far as the top end just makes me want to keep tweaking it . Last summer we added a very nice manual lift mount to the boat with a two inch set back. We raised the motor about 2 inches and were able to get a couple more mph out of t before the dreaded porpoise reared its ugly head . There is more to be had lift wise but we stopped at two for now . To be sure we were not running too high for the water pickup I utilized a little trick I saw at a hydro race and re routed the water exhaust port into the boat and thru the hull to my immediate right . I can actually see the stream as well as feel the heat with my hand to monitor the engine temp manually as it were.
To describe our limit i can best say that just when i hit that last little bit of trim in the up button at about 38 mph you can literally feel the boat free up from the water and start to surge ahead . Unfortunately  that is when the porpoising starts at about 40 mph. The feeling is that the boat starts to skip as the prop digs in , the bow raises , prop comes out of the water , nose comes down and then repeat . This is an exaggeration of the motions but that is what it feels like and i think you can see a bit of what i'm trying to explain in the videos i've added .  All speeds are recorded via GPS and my rpm is 5100 . The sweet spot for my 1994 Johnson 50 is about 5400 btw.
No someone gave me a interesting thought which i wanted to run by you all and see what you thought. He surmised that with the rear of the boat being completely flat that the drag at the stern might be one of my problems and perhaps a experiment might be in order . We all are aware of boats that run " on the pad " such as a Hydro Stream or Allison . His ideas was that if perhaps we could build into the bottom a small angled pad that the boat could get up on and free up some of that drag. Nothing like a deep V but just a gradual angles pad under the boat . We haven't talked about size or anything but perhaps something 18 or 24 inched wide at the stern and extending forward 24 inches or so with a total thickness of an inch or two at the rear. Its just an idea and would not be too hard to fabricate or install .
In any event we are having a ball with the boat and could leave it alone and be very happy but hot rodders whether on land or sea just have to tweak to be happy . I've messed with my road toy for 18 years now and still can think of things I want to do .
As usual i appreciate any input and I will be more active checking in with what is going on with you all .

https://youtu.be/UftPvxYacuA

https://youtu.be/eYH2mNHITbU

[rogerduncan100]

Looks like you've made a lot of progress with your boat!

If you installed a two foot wide angled pad at the transom it would definitely need to be functioning in opposition (force-wise) the the whale tail on the motor. Without the whale tail I think the angled pad wouldn't work at all because it would be like having a hook in the keel. With the whale tail trimmed right you could balance on it and on the the pad and the boat might ride like a v-bottom. You probably thought of this already but I thought I'd chime in anyhow.

Regards!   

[randyt]

Yes we were able to get quite a bit done and as I mentioned the boat is doing everything we want but were just looking for that little bit more. Your comments on the relationship between a added pad and the rear fin males a lot of sense . I am sure we will have a lot of experimenting to do with the various adjustments available to us . With the engine jack plate, adjustable smart tabs and the rear " dole " fin we should be able to make some changes , hopefully mostly good Thanks for your input and response .

[randyt]

Out of curiosity does anyone know when the Minimost XL was first designed ? people ask me about that some times and i just say sometime in the 50's but im just guessing .

[58 Johnson]

Out of curiosity does anyone know when the Minimost XL was first designed ? people ask me about that some times and i just say sometime in the 50's but im just guessing .

Be sure to look around the MSF site.  There are lots of references and a couple of videos about the designer William Jackson.  The answer to your question is... “it depends”. 

[randyt]

I did delve into that quite a bit , even freezing some of the frame grabs in the video but the magazine article never showed the date . I think for the time being I wlll use " late 50's " until i find more definite info . 

[jmuskoka]

Hi Randy.....I am slowly getting things around here back on line and updated after a real crappy 2019!   January 18 2019  my retina blew up at the Toronto Boat Show and I am still having surgery....January 31 will mark the one year passing of my wife, October 15 saw my house burn down and on October 31 my insurance company decided to put a hold on my claim.  The good news is that 2020 is off to a WAY better start!    My very expensive lawyer is taking on my Insurance Company, my personal life is on an upswing and it's time to party!!!!!! 

So......here we GO!!!!!!!

Have you seen this?

https://www.youtube.com/watch?v=OJVsxMDBJV0

and yes.....I was the one who upscaled the Mini Most to the Mini Most XL......certainly not a big revelation in the boat design world, but the larger size seems to fill a need for many seaflea people!  Your own boat looks terrific!

Chris

[randyt]

So glad to see things have turned around . Having such a positive outlook on the future certainly pays credence to your personal strength and constitution.

I have watched the video you listed and found it quite interesting and he certainly was quite an interesting and accomplished individual . I kept trying to pick up and mention of the minimost design to get a “ birth date “. So based on your comments can it be said that the Minimost is a 50’s design with a redo by you in the early 70’s ? Your modifications to the original design certainly accomplished your goal of making the boat more versatile as I can take two adults for a spirited ride , tow a tube full of kids or adults or take a slow cruise up river . Thanks for your efforts !

[randyt]

Looks like you've made a lot of progress with your boat!

If you installed a two foot wide angled pad at the transom it would definitely need to be functioning in opposition (force-wise) the the whale tail on the motor. Without the whale tail I think the angled pad wouldn't work at all because it would be like having a hook in the keel. With the whale tail trimmed right you could balance on it and on the the pad and the boat might ride like a v-bottom. You probably thought of this already but I thought I'd chime in anyhow.

Regards!

I think you certainly see where we are trying to go with the pad experiment . The first question would be the size specifications for the pad itself . Think of it as basically a wedge shape .Would a gradual rise from zero to say 2 inches thick ( deep ) at the stern , perhaps 36 inches long and 12 to 18 inches wide make a difference ?  We don't want to make it too unstable , just free it up a little bit so we can take advantage of the extra power and not have to shut down at 40 mph when the porpoising starts in earnest. I would like to perhaps get as much as 10 more mph out of it if possible or anything close to that .   I'm sure it goes without saying it that we are totally novices when it comes to a boat like this and are just enjoying the process of trying to get what we can out of it . Thanks for the thoughts .

[rogerduncan100]

Randy, take a look at this thread on V-bottoms. Maybe with the right shaped wedge you could turn your boat into one.

https://muskokaseaflea.ca/bb/index.php?topic=1623.msg10913#msg10913

[randyt]

That entire page was interesting, thank you .

[randyt]

Over this past short Xmas visit back to Ct we did a few improvements to the boat . We scrapped the original 1994 Johnson control cables that were 16 ft long for a pair of brand new 10' units . The improvement in the feel and movement of the of the levers was a noticeable improvement .
We also took three out of the four leafs in our trailer suspension out as it as originally designed for a 21 ft boat before we cut it down to our size . With the small amount of weight that our craft has compared to what it was designed for there was very little give over rough roads and the boat got bounced around a lot . With the one leaf it really does the job nicely .
The modification that i really was happy with was changing over to a smaller steering wheel. With the cramped quarters of the original 15 inch wheel sliding ones legs under the wheel and forward under the bow was a real squeeze . What most concerned me was that in the event of a needed quick escape from the boat or if there was a flip of some type having he lower body trapped under the wheel could lead to big problems . Its still tight , no doubt , but its a good deal better than before .
Looking forward to getting back out there in mid may and continue with the development .